[jira] [Commented] (FLINK-12887) Schedule UnfencedMessage would lost envelope info

["Till Rohrmann (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-12887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16867023#comment-16867023 ] 

Till Rohrmann commented on FLINK-12887:
---------------------------------------

I think the current contract is that you cannot schedule an unfenced message. That's why there is only {{runAsyncWithoutFencing}} and {{callAsyncWithoutFencing}} and no {{scheduleRunAsyncWithoutFencing}}. If there is no delay for the {{RunAsync}} or {{CallAsync}}, they would be directly executed. Only if delay is {{> 0}} you would run into this case. Thus, I think it is not a real problem at the moment.

Have you experienced a problem with that or is this more of a theoretical consideration if we would add a {{scheduleRunAsyncWithoutFencing}} method [~Tison]?

> Schedule UnfencedMessage would lost envelope info 
> --------------------------------------------------
>
>                 Key: FLINK-12887
>                 URL: https://issues.apache.org/jira/browse/FLINK-12887
>             Project: Flink
>          Issue Type: Bug
>          Components: Runtime / Coordination
>    Affects Versions: 1.9.0
>            Reporter: TisonKun
>            Priority: Major
>
> We provide {{runAsync}}, {{callAsync}} and {{scheduleRunAsync}} for {{MainThreadExecutable}}, while providing {{runAsyncWithoutFencing}} and {{callAsyncWithoutFencing}} additionally for {{FencedMainThreadExecutable}}.
> Let's think about a case when we want to schedule a unfenced runnable or any other unfenced message(currently, we don't have such code path but it's semantically valid.). 
> 1. {{FencedAkkaRpcActor}} received an unfenced runnable with delay
> 2. It extracted the runnable from unfenced message and call {{super.handleRpcMessage}}.
> 3. {{AkkaRpcActor}} enveloped the message and schedule it by {{AkkaRpcActor#L410}}.
> However, {{FencedAkkaRpcActor#envelopeSelfMessage}} was called for envelope. Thus the unfenced message now become a fenced message.
> We can anyway implement {{scheduleRunAsyncWithoutFencing}} to schedule unfenced message directly by {{actorsystem.scheduler.scheduleOnce(..., dispatcher)}}, but with current codebase I notice that {{RunAsync}} has a wried {{atTimeNanos}}(i.e., delay) property. Ideally how to schedule a message is shown on what params ScheduleExecutorService called with, at least we cannot extract an unfenced message and envelop it into a fence message and then schedule it, which goes into wrong semantic.
> cc [~till.rohrmann]



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